Fmla paperwork

It is so confusing i dont work but my fiance does and he wants to take time off when the babys born to help me but we're so confused ln how to do everything. I know he has to fill everything out and then have my ob fill her part out but the section where it says when he wants to start his leave and then when he wants to go back work we dont know what to put there my dr said theres a chance of me having baby early due to high blood pressure but theyre going to try to keep him in till 39 weeks sp it could be anytime help me out and let me know what to do